Methods and apparatus for soft sand testing



Jan. 21, 1969 M P, LEBOURG 3,422,573

METHODS AND APPARATUS FOR SOFT SAND TESTING m mzi Sheet of 2 Filed June9. 1966 Mauf/re Zeoury ATTORNEY 1969 M. P. LEBOURG METHODS AND APPARATUSFOR SOFT SAND TESTING Sheet 2 Filed June 9, 1966 Mad/Me P. Zebou/yLVVENTOR BYZ/MJX ATTORNEY United States Patent Office 3,422,673 PatentedJan. 21, 1969 17 Claims ABSTRACT OF THE DISCLOSURE Methods and apparatusfor testing soft sand earth formations traversed by a fluid filled wellbore are described. According to the methods, a packer on a pipe stringis lowered into the well bore and the packer is expanded to isolate aformation zone, the zone being also isolated from the pipe string. Fluidpressure in the isolated zone is then measured over a period of time.Further, fluid circulation can be maintained above the packer, and thepipe string can be kept in motion. The apparatus includes an inflatablepacker which can be expanded by fluid pressure in the pipe string, thepacker having a blocked bore. Pressure recorders are provided to measurepressures in the zone which is completely isolated by the packer and theblocked bore during the test.

This invention relates to methods and apparatus for obtaining valuabledata concerning subterranean well formations having poor structuralcharacteristics and/or where the well bore is deviated from thevertical, to an extent that ordinary drill stem testing is undesirable.

In geographical areas where it is common to drill well bores intounconsolidated sand or iheaving shale formations, for example, the GulfCoast area of the United States, ordinary drill stem testing has neverbeen popular because of the substantial risk of losing the tool in thewell bore. For example, if the hydrostatic pressure of the fluids in anisolated zone is greatly reduced below the formation fluid pressure, theunconsolidated sand or shale tends to dump out into the well bore andfill either a cased or an open hole.

In geographical areas wthere it is common to drill excessively deviatedwell bores through permeable formation zones, differential pressuresticking of the drill pipe can occur. Moreover, there can be acombination of these circumstances where excessively deviated well boresare drilled into unconsolidated sand or heaving shale formations.

With proper hydrostatic pressure control, these formations can be loggedwith conventional wireline electrical logging tools to obtainlithography, formation density and porosity. However, a good measurementof the actual hydraulic pressure within the formation is not ob tained,a measurement which is highly useful in the analysis of a formationscommercial prospects.

It is accordingly an object of the present invention to provide new andimproved methods and apparatus for gathering well data concerning theabove-mentioned types of formations without the risk of losing thetesting tools and wherein the fluid pressures within such formation canbe determined.

In general, the method of the present invention includes the steps oflowering a well packer on a pipe string into a well bore which traversesthe earth formation to be tested, expanding the packer to isolate a zoneof the well bore from fluids in the remainder of the well bore,measuring the pressures of fluids in the isolated zone during a timeinterval, and maintaining circulation of fluids in the well bore duringthe test. Additionally, the method of the present invention may includethe step of moving the pipe string while the zone is isolated and thefurther step of measuring at least one physical characteristic of theearth formation being tested after the pressures of fluids in theisolated zone has been measured.

The apparatus of the present invention is generally described ascomprising logging means for sensing, measuring and recording propertiesof the well formation. Tubular members having a closed bore areconnected to said logging means and the tubular members are rotativelycoupled to a pipe string extending upwardly to the earths surface.Inflatable packing means on the tubular members is expandable inresponse to fluid pressure for isolating a selected formation interval,the pressure acting through an inflation passage which communicates thepacking means with the interior of the pipe string. Means are providedfor recording fluid pressure changes of the fluids in the well boreadjacent the isolated formation interval and a circulation passage meansin the members permits circulation of fluids through the pipe string andwell annulus while the packing means is expanded.

A full disclosure of an embodiment of the invention follows to faciliatea full understanding of the concepts involved. This disclosure includesthe attached drawings in which:

FIGURE 1 is an elevational view of one embodiment of the invention shownin connection with the well bore;

FIGURE 2 is an enlarged longitudinal sectional view of the upper portionof the apparatus shown in FIG- URE 1;

FIGURE 3 is longitudinal partial sectional view of the lower portion ofthe apparatus shown in FIGURE 1, FIGURE 3 forming a lower confirmationof FIGURE 2; and

FIGURE 4 is a sectional view of the upper portion of the apparatus shownin FIGURE 2 with parts of the apparatus in operative positions to test aformation zone.

Referring initially to FIGURE 1, the apparatus of the present inventionis generally designated by the numeral 10 and is shown suspended withina well conduit 11 on a running-in string '12 which extends upwardly tothe earths surface. The apparatus 10 includes an inner tubular member 13connected at its upper end by a coupling 14 to the running-in string 12and telescopically disposed within an outer tubular member 15 formovement between the expanded and contracted relative positions. Aninflatable packer element 16 is mounted on the members 13, 15 and isadapted for lateral expansion into sealing engagement with the wall ofthe well conduit 11 to isolate a selected formation zone.

A section of perforated anchor pipe 20 is connected to the lower end ofthe outer tubular member 15 and has a plurality of ports 21 forcommunicating the bore of the anchor pipe 20 with the well fluids in theannular space below the packer element 16. Contained within the bore ofthe anchor pipe 20 is at least one pressure recorder 22 for obtaining apermanent record of fluid pressure changes versus elapsed time in aconventional manner.

An electrical logging device 25 forms a lower portion of the apparatus10 and contains suitable instrumentation, to be discussed in more detailhereafter, for sensing and recording indicia from which well parameterssuch as lithography, density and porosity can be determined.

Referring now toFIGURE 2, the inner tubular member 13 is slidablyreceived within the bore 26 of the outer tubular member 15 fortelescoping movement therein. The inner member has a box portion 30 atits upper end which is connected to the lower end of the running-instring 12 by a rotatable coupling 14. An outwardly extending flange 31on the running-in string 12 is received between antifriction bearings32, 33 which are confined 3 within the box portion by a threaded ring34. A suitable seal element is positioned at the lower end of the string12 between it and the box portion 30. In this manner, the running-instring 12 is rotatable relative to the tubular members 13, 15 while thecoupling 14 provides a fluid-tight connection therebetween.

A partition or barrier 36 segregates the interior of the inner memberinto upper and lower bores 37, 38, respectively, and functions to blockfluid communication therebetween, thereby prohibiting any fluid flowlongitudinally through the tubular members. A plurality of ports orpassageways 39 are provided in the inner tubular member 13 intermediatethe box portion 30 and the barrier 36 and are spaced above the upper endof the outer tubular member 15 when the members are expanded as shown inFIGURE 2 to establish fluid communication between the interior of therunning-in string 12 and the well annulus above the packer element 16. Alower portion 40 of the inner member 13 extends downwardly below thebarrier 36 and a bypass port 41 extends through the wall of the lowerportion 40 below the barrier.

The bore 26 of the outer member 15 is enlarged intermediate the endsthereof to provide a chamber section 42 which slidably receives anoutwardly extending flange 43 at the lower end of the inner member 13.Interengaging splines 44, 45 on the wall of the chamber section 42 andthe outer periphery of the flange 43, respectively, corotatively securethe inner and outer members together. A bypass passageway 46 extendslaterally in the wall of the outer member 15 and registers with theinner member bypass port 41 when the members are expanded to permit wellfluids to bypass through the members and around the packer element 16via the anchor pipe perforations 21, the bore 26 of the outer member 15,the lower bore 38 of the inner member 13 and the bypass ports orpassageways 41, 46.

The outer member 15 has a tubular section 47 which extends downwardlyfrom the chamber section 42 and is threadedly connected to its lower endto an annular sub which forms the lower portion 48 of the outer member15. The lower portion has stepped outer surfaces which slidably receivea packer return sleeve 50 and suitable seal elements 51 fluidly sealbetween the sleeve 50 and the outer surfaces of the lower portion 48.

The packer element 16, in the form of an annular elastomer sleeve, ismounted around the outer member 15 with its upper end 52 secured andsealed within a recess 53 in the outer member and its lower end 54secured and sealed within a recess 55 in the return sleeve 50. Thepacker element 16 is adapted for lateral expansion responsive to fluidpressures exerted on the internal surfaces thereof into sealingengagement with the wall of the well conduit 11.

An inflation passageway 57 in the outer member 15 provides fluidcommunication to the space 58 between the packer element 16 and theouter member 15 and opens into the bore 26 of the outer member betweenupper and lower spaced seal elements 59, 60 between the members. Theinflation passageway 57 registers with a port 58 in the inner memberabove the barrier 36 when the members are expanded so that fluidpressures within and without the packer element can equalize duringrun-in. Alternatively, the inflation passageway 57 registers with one ofthe ports 39 in the inner member 13 when the members are contracted(FIG. 4) whereby fluid pressure applied to the fluids within therunning-in string 12 will act to inflate the packer element 16. As thepacker element 16 is inflated, the sleeve 50 can move longitudinally onthe lower portion 48 to accommodate changes in length of the packerelement.

A circulation passageway 61 is also provided in the outer member 15 forcirculation of fluids between the interior of the running-in string 12and the well annulus above the packer element 16 when the members 13, 15are in their contracted relative position. The passageway 61 opens atits upper end into the bore 26 of the outer member between thelongitudinally spaced seal elements 59, 60 and the lower end of thepassageway 61 intersects the lateral bypass passageway 46. In thecontracted position, the circulation passageway 61 registers with one ofthe ports 39 in the inner member 13 to place the passageway incommunication with the interior of the running-in string 12 via theupper bore 37 of the inner member.

A unidirectional flow valve 62 is positioned within the circulationpassageway 61, the valve including a valve element 63 which is pressedupwardly against a companion seat 64 by a compression spring 65 seatedbetween a shoulder 66 in the passageway and the lower face of the valvemember. The compression spring 65 exerts a predetermined upward force onthe valve element 63 so that a known fluid pressure is required to movethe valve element downwardly away from its seat to open the passageway61 to fluid flow. It is preferable that the pressure required to openthe valve 62 is at least as great as the pressure required to fullyinflate the packer element 16 for assurance that the packer element ismaintained in sealing engagement with the wall of the well conduit 11when the valve opens.

As shown in FIGURES 2 and 3, the perforated anchor pipe 20 isdependently secured to the lower portion 48 of the outer tubular member15 and has a plurality of lateral ports 21 arranged to communicate theinterior of the anchor pipe with the well annulus below the packermember 16. Suitably secured within the anchor pipe 20 is one or morepressure recorders 22 of the type shown in US. Patent No. 2,816,440 forrecording pressure changes of the well fluids below the packer elementas a function of elapsed time.

Dependently coupled to the lower end of the anchor pipe 20 is theformation logging instrument 25 on which is secured a pad assembly 70and a switch assembly 71. The more specific details of the logginginstrument form no part of the present invention and are fully set forthin application Ser. No. 327,947 of Maurice P. Lebourg, filed Dec. 4,1963, now US. Patent No. 3,306,102. Briefly described, the formationlogging instrument includes an outer housing 72, preferably made ofmetal, which encloses batteries 73, a data recorder 74 and any one ormore of conventional logging instruments such as, for example, a gammaray logging instrument 75 and electrical resistivity measuring circuits76 in separate compartments. The logging instruments and circuits eachdete'ct particular properties which are characteristic of the fluidswithin the formations adjacent the logging instruments and convert thedetected characteristics into electrical signals representative thereof.The electrical signals are then recorded on a data recorder 74 which maybe any conventional machine normally used in the art. A typicalresistivity measuring apparatus is shown in US. Patent No. 2,712,629,and a typical gamma ray logging apparatus is shown in US. Patent No.2,349,225.

The pad assembly 70 includes an insulated wall engaging pad 77 attachedto the housing 72 by a strong bowspring 78 which can be coated with anelectrical insulating material such as epoxy resin. A plurality ofspaced apart electrodes 79 are embedded in the outer surface of the pad77, the electrodes being either flush with the face of the pad orslightly recessed therein.

At the lower end of the logging instrument 25 is the switching assembly71 to selectively turn on electical power to the various componentswithin the logging instrument. The switching assembly 71 includes arelay assembly 80 which can be a conventionally arranged holding circuitfor maintaining power to the components after momentary actuation of theswitching assembly 71.

The switching assembly includes resilient electrical contacts 82 spacedapart from one another in such a manner that a male conductor 83 willbridge the gap between the contacts 82 whenever the contact members andconductor are engaged. Of course, the male conductor and the resilientcontacts are electrically insulated from the housing 62 by suitablemeans (not shown).

The male conductor 83 is centrally located on top of an enlarged portion84 of a cylindrical plunger member 85 which is slidably received withina bore 86 at the lower end of the housing 72. A compression spring 87encircles the plunger and presses the plunger downwardly so that themale conductor 83 is normally spaced away from the resilient contacts82. A lower portion of the plunger member 85 is enlarged to provide abottom contact member 88 and it will be appreciated that on upward forceon the bottom contact member 88 suflicient to overcome the force of thespring 87 will move the plunger member 85 upwardly and the maleconductor 83 into engagement with the resilient contacts 82.

Although it is not necessary, it is preferred that the pad assembly 70be in a retracted position within a housing recess 90 for its protectionwhen lowering the apparatus into the well bore 11. For this purpose, theends of the bow-spring 78 are fixedly attached to hinge members 91, 92which are slidably received in longitudinal slots 93, 94 cut in thesides at both ends of the recess 90. When the pad is retracted, thelower hinge member 92 is held at the bottom of slots 94 by a shear pin(not shown) which is strong enough to constrain the bow-spring 78 in itsextended or retracted position. An actuating rod 96 is received within alongitudinal bore which extends through a portion of the housing 72 fromthe lower end of the recess 90 to the lower end of the switch assembly71. The upper end of the rod 96 contacts the lower hinge member 92 andthe lower end rests freely on the upper side of the bottom contactmember 88. Thus, when the bottom contact member is moved upwardly by apredetermined force, the thrust rod will move upwardly to shear the pin95. Failure of the shear pin frees the lower hinge member and permits itto move upwardly in the slots 94 as the bow-spring 78 moves the padmember 77 outwardly into engagement with the well bore wall.

The invention is operated as follows. The apparatus 10, assembled asshown in the drawings, is lowered into the well bore 11 to a formationzone or interval to be investigated. While lowering, the inner and outermembers 13, 15 are in their expanded position with the ports 39'communicating the running-in string 12 with well annulus above thepacking element 16 and the bypass passageways 41, 46 are in registry. Asthe apparatus moves downwardly, fluids in the well bore can bypass thepacker element 16 both around the exterior thereof and through theapparatus via the bypass passageways 41, 46 as previously described.Also, well fluids can enter the runningin string 12 through the ports 39to fill the string as the apparatus is lowered.

When the bottom of the well bore is reached, the bottom contact member88 engages the bottom of the bore hole and the weight of the apparatusforces the bottom contact member 88 upwardly, thereby closing the switch71 to activate the relay assembly 80 in preparation for supplying powerfrom the batteries 73 to the data recorder 74, the gamma ray logginginstrument 75 and the resistivity logging circuits 76. Upward movementof the bottom contact member also serves to release the pad assembly 70from its retracted position, thereby permitting the pad 77 to shiftoutwardly into engagement with the well bore wall.

With the lower part of the apparatus 10 and thus the outer memberresting on bottom, further downward movement of the running-in string 12serves to telescope the inner and outer members 13, 15 to theircontracted position, shown in FIG. 4, wherein the inner member ports 39register with the circulation passageway 61 and the inflation passageway57 in the outer member 15. The packer bypass passageways 41, 46 aresealed off from one another by a seal element 67 and the barrier 36 inthe inner member 13 continues to prohibit fluid flow longitudinallythrough the members.

Pump pressure is then applied at the earths surface to the fluids withinthe running-in string 12, the pressure acting via the inflationpassageway 57 to expand the packer element 16 into sealing engagementwith the well bore wall. This pressure also acts via the passageway 61against the valve element 62 but the upward force of the spring 65resists movement of the valve element until the unit pressure thereonexceeds the unit pressure required to fully expand the packer element16, which can be, for example, 500 psi.

When the packer element 16 is fully expanded to isolate the formationinterval, further increased pump pressure acts to open the valve 62 andthereby communicate the running-in string with the well annulus justabove the packer element so that continuous mud circulation can bemaintained. The running-in string 12 can be kept in rotative motion dueto the coupling 14 between the string and the inner member 13 to combatdiflierential pressure sticking.

Once the packer element 16 is inflated, the fluid pressure in the wellannulus therebelow will increase slightly to reflect the setting of thepacker element and the trapping of the fluid at its hydrostaticpressure. Thereafter the space below the packer element is isolated sothat pressure decay can occur, e.g., the pressure of fluids in the wellbore adjacent the isolated interval will decrease as fluid in the wellbore continues to enter the formation, thus causing the well bore fluidpressure to gradually approach or equalize to the lower pressure of thefluids in the formation. The pressure decay function can be used in amanner similar to the pressure build-up function measured in ordinarydrill stem testing to accurately determine the true or virgin formationfluid pressure in a known manner. Moreover, the pressure decaymeasurements can be utilize-d in the detection of formation anomaliessuch as faults and fluid contact points.

Hence, over a period of time, the pressure of fluids in the formation ismeasured and recorded on the pressure recorder 22, yet the pressurewithin the well bore adjacent the formation is never less than theformation fluid pressure, thus preserving the integrity of theformations structural characteristics and preventing dumping or heavingof formation material into the well bore. After a sufiicient period oftime to measure the pressure decay function, the running-in string 12 ispicked up to move the members 13, 15 to their expanded position. Thismovement serves to open the bypass passages 41, 46 to equalize pressuresacross the packer element. Then the packer element 16 is deflated forupward movement of the apparatus within the well bore.

After deflating the packer element, the testing apparatus is pulledupwardly at a desired rate of speed to obtain a series of logging datacharacteristic of the formations along the test interval. As the bottomcontact member 88 lifts off bottom, the plunger member 85 is presseddownwardly by the spring 87 and the switch 71 opens, but the relaysclose a circuit between the batteries 73 and the various instrumentcircuitry. If desired, the apparatus can be lowered again to obtainadditional series of logging data.

It will now be apparent that new and improved methods and apparatus havebeen disclosed for gathering well data such as lithography, density andporosity of a subterranean well formation as well as the true hydraulicpressures of fluids within the formation. The apparatus is constructedand arranged in a manner whereby lost tool risks are minimal. Sincecertain changes may be made in the embodiment disclosed withoutdeparting from the inventive concept, it is intended that all mattercontained in the foregoing description or shown in the attached drawingSshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for use in testing earth formations traversed by a wellbore comprising: a body carrying inflatable packer means and adapted forconnection with a string of pipe extending to the earths surface, saidpacker means being expandable in response to fluid pressure in the pipestring for isolating a selected formation interval; inflation passagemeans in said body for communicating said packer means with the interiorof the pipe string, said body having a closed off bore to preventcommunication between the formation interval and the pipe string at alltimes during testing; and recorder means carried by said body forrecording changes in fluid pressure below said packer means and saidclosed bore to obtain a record thereof as a function of lapsed timeafter the packer means isolates the formation interval, therebyobtaining a record of changing pressures as fluid pressures in the wellbore below said packer means and said closed bore tend to equalize withfluid pressures in the isolated formation interval.

2. Apparatus as recited in claim 1 further including passage means insaid body for circulating fluids through the pipe string and the wellannulus above said isolated formation interval while said recordingmeans obtains a pressure record.

3. Apparatus as recited in claim 2 further including pressure responsivemeans in said circulation passage means operable to open saidcirculation passage means at a pressure at least as great as thepressure required to fully expand said packer means.

4. Apparatus as recited in claim 1 further including coupling means onsaid body for connecting said body to the pipe string, said couplingmeans including relatively rotatable parts whereby the pipe string canbe rotated relative to the body while said recorder means obtains apressure record.

5. Apparatus as recited in claim 1 further including bypass passagemeans in said body permitting fluid passage between the well annulusspaces above and below said packer means; and means for selectivelyclosing said bypass passage means.

6. Apparatus for use in testing and logging earth formations traversedby a well bore comprising: logging means for sensing, measuring, andrecording characteristic properties of a well formation; tubular membersconnected to said logging means, said members having a closed bore;means for coupling said tubular members to a pipe string extendingupward to the earths surface; inflatable packer means on said membersexpandable in response to fluid pressure for isolating a selectedformation zone, said closed bore at all times during a test preventingfluid communication between the pipe string and the isolated formationzone; inflation passage means communicating said packer means with theinterior of the pipe string; and means for recording changes in fluidpressure below said packer means and said closed bore to obtain a recordthereof as a function of lapsed time after the packer means isolates theformation zone.

7. Apparatus as recited in claim 6 further including passage means insaid members for circulating fluids between the pipe string and the wellannulus above the packer means while said recording means obtains apressure record.

8. Apparatus as recited in claim 7 further including a pressureresponsive valve means in said circulation passage means operable toopen said circulation passage means at a pressure at least as great asthe pressure required to fully expand said packer means.

9. Apparatus as recited in claim 6 wherein said coupling means includesrelatively rotatable parts whereby the pipe string can be placed inmotion relative to said tubular members.

10. Apparatus as recited in claim 6 further including bypass passagemeans permitting fluid passage. between the well annulus spaces aboveand below said packer means; and means for selectively closing saidbypass passage means.

11. A well tool comprising: innerand outer tubular memberstelescopically movable between expanded and contracted relativepositions, said members having means blocking fluid flow throughtherethrough; means for coupling said members to a pipe string extendingupwardly to the earths surface; inflatable packer means on said membersexpandable in response to fluid pressure for isolating a selectedformation interval; inflation passage means communicating said packermeans with the pipe string whereby fluid pressure applied through thepipe string is effective to inflate said packer means; passage means insaid members cooperable in at least one of said relative positions forcommunicating the pipe string with the well annulus above said packermeans so that fluids can be circulated therethrough; and means forrecording fluid pressures below said packer means and said blockingmeans to obtain a record of said pressures after said packer meansisolates the formation interval.

12. Apparatus as recited in claim 11 wherein said coupling meansincludes relatively movable parts whereby the pipe string can be movedrelative to said tubular members while said packer means is expanded.

13. Apparatus as recited in claim 11 further including bypass passagemeans permitting fluid passage between the annulus spaces above andbelow said packer means; and means for selective opening and closingsaid bypass passage means.

14. Apparatus as recited in claim 11 further including pressureresponsive valve means in said circulation passage means operable toopen said circulation passage means at a pressure at least as great asthe pressure re quired to inflate said packer means.

15. A method of testing subterranean earth formations traversed by afluid filled well bore, comprising the steps of: lowering a well packeron a pipe string into the well bore; expanding the packer to isolate azone of the well bore from fluids in the remainder of the well bores;maintaining the zone isolated from the interior of the pipe stringduring the test; measuring the pressure of fluids in the isolated zoneduring a time interval; and circulating fluids through the pipe stringand the well annulus in the remainder of the well bore while the packeris expanded.

16. The method recited in claim 15 including the further step of: movingthe pipe string while the packer is expanded.

17. The method recited in claim 15 including the further step of:measuring at least one physical property of the earth formation afterthe pressure of fluids in the isolated zone has been measured.

References Cited UNITED STATES PATENTS 2,158,569 5/1939 Bowen 73-1552,503,557 4/1950 McKinley. 2,564,198 8/1951 Elkins 73l55 3,115,77512/1963 Russell 73-152 OTHER REFERENCES Bleakley, W. B.: Moderndrill-stem testing from The Oil and Gas Journal, vol. 56, No. 51, Dec.22, 1958, pp. 58 and 59.

RICHARD C. QUEISSER, Primary Examiner.

JERRY W. MYRACLE, Assistant Examiner.

US. Cl. X.R. 166187, 196

